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Patent CN115230365B

Updated November 7, 2026

Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings

Traditional wire-o or spiral binding requires heavy machinery and fixed coil sizes. This patent describes a simpler alternative: soft plastic rings made from flat strips. A strip has a base band and tooth-like extensions. You align the pages, push the teeth through the holes, and weld the tip to the base. The result is a round, soft plastic ring that holds the book together. It’s scalable, uses standard injection molding for parts, and simplifies the binding process for brands and wholesalers.

  • China invention patent - active
  • No filings outside China
  • Stationery & Binding
  • LDPE rings, ultrasonic welding
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Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - product render

📚

Flexible Binding

Rings are formed during assembly, allowing custom page counts per book.

🔗

Welded Loop

Comb-like teeth pass through holes and weld to the base band to close the ring.

🏭

Simple Manufacturing

Consumables are injection-molded; assembly requires only alignment and ultrasonic welding.

💎

Soft & Durable

Uses Low-Density Polyethylene (LDPE) for high gloss and elastic recovery.

🔥 Popularity – views

Bring this product to market

  1. ✓ Patent review Patent family and legal status reviewed in the relevant jurisdictions.
  2. 2 Product brief · now How it works, uses and options written up
  3. 3 Prototype First samples for buyers to review
  4. 4 Pilot run Small first batch for launch customers
  5. 5 Volume production Repeat orders at scale

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The problem

Standard loose-leaf binders often use metal wires or rigid plastic coils that require specialized opening/closing tools or large machinery to install. For manufacturers producing custom notebooks, journals, or educational kits, this creates bottlenecks: you must stock many different coil sizes to match varying page counts, and the installation equipment is expensive and bulky. Additionally, rigid coils can snag clothing or feel harsh against the hand when reading. There is a need for a binding method that is simple to execute, adaptable to variable thicknesses, and uses softer, safer materials.

The solution

The patent introduces a “binding ring consumable”—a flat strip of plastic with two distinct zones: a base belt part (flat backing) and an arc part connected to tooth tips. These teeth are arranged like a comb.

  1. Preparation: Pages are punched with rectangular or square holes along one edge.
  2. Insertion: The tooth tips of the consumable are pushed through the aligned holes of the stacked pages.
  3. Formation: The arc part bends around to form a near-circular loop. The tooth tip overlaps the base belt part.
  4. Fixation: Ultrasonic welding joins the tooth tip to the base belt. After welding, excess positioning bosses may be trimmed off.

This creates a closed, soft plastic ring that holds the pages securely. Because the ring is formed around the pages, it naturally accommodates the exact thickness of the stack, eliminating the need for multiple pre-sized coil diameters.

Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent drawing - assembled booklet
Fig. 1 - Perspective and side views of the finished loose-leaf booklet.

Who it is for

  • Notebook and Journal Brands: Companies launching new product lines who want to offer customizable page counts without stocking dozens of coil sizes.
  • Educational Kit Manufacturers: Producers of workbooks or student journals where page numbers vary by subject or grade level; this system simplifies assembly.
  • Promotional Product Suppliers: Agencies creating branded notebooks for events; the simple assembly line allows for quick turnaround on custom orders.
  • Office Supply Wholesalers: Distributors looking for a differentiated, softer-touch alternative to standard wire-o or spiral bindings for corporate clients.

How it works

The main parts

No.PartWhat it does
1Booklet AssemblyThe final product consisting of pages and rings.
2Loose LeavesPaper, fabric, or leather sheets with punched holes.
3Through HolesRectangular/square openings in the pages for the ring teeth.
4Binding RingThe final circular loop holding the pages.
41Base Belt PartFlat strip section; includes positioning features.
42Arc PartCurved section that forms the body of the ring.
43Tooth TipPointed end that passes through holes and welds to the base.
411/412Positioning Bosses/DotsFeatures on the base belt to align the tooth tip before welding.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent drawing - binding consumable
Fig. 2 - Structure of the binding ring consumable strip.

Operating steps

  1. Stack and Align: Gather the desired number of pages and align their punched holes.
  2. Thread: Insert the tooth tips (43) of the consumable strip through the holes (3).
  3. Wrap: Bend the arc part (42) so the tooth tip meets the base belt part (41).
  4. Weld: Use ultrasonic equipment to fuse the tooth tip to the base belt, closing the loop.
  5. Trim (Optional): Remove any protruding positioning bosses if specified in the design variant.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent drawing - assembly process
Fig. 3 - Step-by-step diagram of threading, wrapping, and welding.

Applications

Student Workbooks

School supplies often require specific page counts for math or language exercises. This binding allows schools or publishers to print exactly the needed number of sheets and bind them quickly without adjusting machine settings for different coil diameters.

Corporate Journals

Businesses ordering branded notebooks for conferences benefit from the soft LDPE material, which feels premium and doesn’t snag on suit pockets or bags. The uniform look of the rings enhances brand presentation.

DIY Craft Kits

Craft sets for children or hobbyists often include varying amounts of paper or cardstock. The consumable strips can be sold as part of the kit, allowing users to assemble their own booklets with minimal tools (just an adhesive or simple press if adapted, though the patent specifies ultrasonic welding for factory use).

Archival Albums

For photo albums or document storage where the content thickness varies significantly between volumes, this system ensures a tight fit without gaps, protecting contents from shifting or falling out.

Where it is less suitable

  • High-Security Documents: Unlike tamper-evident seals, these rings can potentially be cut or melted open if accessed with tools, making them unsuitable for confidential legal contracts requiring strict integrity.
  • Very Heavy Loads: While LDPE is durable, extremely thick stacks of hardboard or metal sheets may exceed the tensile strength of the plastic ring compared to steel wire-o.
  • Automated High-Speed Lines: If your facility already runs fully automated wire-binding machines, switching to this manual or semi-automatic welding step might slow down throughput unless dedicated ultrasonic stations are installed.

Patent & Production

At a glance

Patent numberCN115230365B (application CN202210938179)
TypeChina invention patent (发明专利) - protects product structure and method
Original titlePlastic soft ring-bound loose-leaf booklet (塑胶软性圈装活页本册)
Patent ownerNingbo Chuangxin Binding Equipment Co., Ltd.
InventorsWang Weijun
Filing date2022-08-05
Grant date2023-09-08
Status (China)In force until at most 2042-08-05 (if annual fees are paid)
Patent familyPublic record shows Chinese filings only - no US, European, Japanese, PCT or other filings listed
Cited by0 later documents
SourceGoogle Patents (search for CN115230365B)

What the claims cover, in plain language

Claim 1 defines a loose-leaf booklet where pages have holes, and a plastic soft binding ring passes through them. The ring is formed from a “binding ring consumable” consisting of three parts: a base belt part (flat), an arc part, and tooth tips. The arc and tooth tips form a comb-like rack. The tooth tip passes through the page hole and is welded to the base belt part to create a circular ring. The arc part has a specific bend (“second direction arc”) and an extension that rises above the base surface.

Claims 2-3 specify angles between the arc/base and arc/tooth tip sections. Claims 4-5 detail positioning features on the base belt (bosses and dots) and corresponding grooves/holes on the tooth tip to ensure accurate alignment before welding. Claim 6 mentions trimming the positioning bosses after welding. Claim 7 identifies Low-Density Polyethylene (LDPE) as the preferred material. Claim 8 states the consumables are made via injection molding. Claim 9 specifies ultrasonic welding as the joining method. Claims 10-11 describe the offset position of the weld and its placement relative to covers/pages. Claims 12-13 define sizing rules: starting inner diameter of 6.5mm, increasing by 1.5mm steps, and the relationship between ring diameter and leaf thickness. Claim 14 sets the height of the extension part at 0.5–1.2mm.

This is a simplified reading for orientation only. The legal scope is defined by the exact claim wording in the official Chinese document.

What this means for US production

This patent was filed in China and is currently in force. The public record shows no US or other foreign counterpart. Therefore, making or selling this specific configuration in China requires the owner’s permission. In the US, since there is no US patent counterpart, the design itself is not restricted by this specific patent. However, general freedom-to-operate analysis is still recommended.

Two points to settle early:

  • Other patents may exist. The stationery and binding industry is competitive. While this specific mechanism appears unique in the public record for this patent, related mechanisms for plastic coil binding or ultrasonic welding of stationery items may be covered by other US patents. A freedom-to-operate (FTO) review is advised before mass production.
  • Material Safety. The patent specifies LDPE. Ensure the resin used meets US standards for office supplies, particularly regarding phthalates or other additives if targeting school markets.

Customization and manufacturing

What can be customized

AreaOptions
Ring DiameterStarting at ~6.5mm inner diameter, scalable in 1.5mm increments per Claim 12.
Page Thickness CapacityDetermined by ring size selection (Inner Dia = Leaf Thickness + 2.5-4mm).
MaterialLDPE is preferred for gloss/elasticity; other plastics possible if they support ultrasonic welding.
ColorPigments can be added during injection molding for brand matching.
Hole ShapeRectangular or square holes (as described in the specification) to fit the tooth width.
FinishHigh gloss (standard for LDPE) or matte finishes via mold texture.

Things to plan for (US market)

  • ASTM F963: Standard Consumer Safety Specification for Toy Safety (if marketed to children under 12). Small parts regulations apply to the rings and pages.
  • California Prop 65: Screening of plastics and pigments for listed chemicals.
  • General Product Safety: Ensuring edges are smooth (post-trimming) to prevent cuts, especially for school use.

How a project runs

  1. Design Validation: Confirm hole dimensions match tooth width; select ring size for target page count.
  2. Mold Making: Create injection molds for the “binding ring consumable” strips.
  3. Sample Run: Produce strips using LDPE; test ultrasonic welding parameters.
  4. Assembly Test: Verify ease of threading and ring closure; check aesthetic finish after boss trimming.
  5. Production Scale-up: Set up injection molding lines and ultrasonic welding stations.

Quantities & timeline

Injection molds for the consumable strips are the primary tooling cost. Ultrasonic welding requires calibrated generators and horns. Cycle times depend on wall thickness of the plastic. Send us your target page counts, color requirements, and estimated volume and we will reply with options.

Patent drawings

Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 1
Fig. 1 - Perspective and side view of the loose-leaf booklet.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 2
Fig. 2 - Structural diagram of the binding ring consumable.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 3
Fig. 3 - Schematic of the binding steps (threading, positioning, welding).
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 4
Fig. 4 - Detailed view of the ring formation.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 5
Fig. 5 - Alternative embodiment or detail view.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 6
Fig. 6 - Component detail.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 7
Fig. 7 - Welding interface detail.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 8
Fig. 8 - Positioning feature detail.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 9
Fig. 9 - Cross-section view.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 10
Fig. 10 - Additional structural detail.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 11
Fig. 11 - Assembly sequence detail.
Plastic Soft Ring-Bound Loose-Leaf Booklet with Injection-Molded Binding Rings - Patent Fig. 12
Fig. 12 - Final product variation.

Drawings reproduced from the public patent document for reference.

Production notes

Tooling and process

Likely requires precision injection molds for the comb-like consumable strips. Heat staking or adhesive bonding stations are typically needed to fuse the tooth tip to the base band. Trimming dies may be necessary to remove positioning bosses after bonding.

Cost drivers

Number of molds depends on ring size variations. Print setup costs apply if branding is added directly to the pages or packaging. Spring and clip quality is not applicable here, but plastic resin consistency affects weld strength. Assembly steps (threading, welding, trimming) drive labor or automation costs.

Prototyping path

We would typically start with 3D-printed samples of the consumable geometry to verify fit. Conduct function and cycle tests on small batches. Perform a print trial for any decorative elements. Off-the-shelf springs are not relevant; focus on testing the plastic elasticity.

What we would change before tooling

We would likely verify the tolerance between the tooth width and the page hole size to prevent jamming. Adjust the ultrasonic welding energy settings to avoid melting through the thin LDPE. Ensure the trimming mechanism cleanly removes bosses without damaging the ring surface.

Common failure points

Hinge fatigue is unlikely in this static ring, but edge hardness and wear could cause tearing if the plastic is too brittle. Seam strength is critical; poor welding leads to ring failure. Ink compatibility matters if printing on the plastic. Cover cracking may occur if the ring is too tight for the page weight.

Frequently asked questions

How is the ring attached to the pages?

The ring is not a pre-made coil. It starts as a flat plastic strip with comb-like teeth. You push the teeth through the holes in your stacked pages, bend the strip into a circle, and then ultrasonically weld the tip of the tooth to the back of the strip. This closes the loop around the pages.

What material is used for the binding rings?

The patent specifically recommends Low-Density Polyethylene (LDPE). This material is chosen for its high gloss, flexibility, and ability to recover from deformation, making the rings durable and pleasant to handle.

Can I choose the size of the ring?

Yes. The design allows for scalability. The patent describes starting with an inner diameter of about 6.5mm and increasing in 1.5mm increments. The correct size is determined by the total thickness of your pages (inner diameter equals leaf thickness plus 2.5–4mm).

Is this binding method difficult to automate?

It involves several steps: punching, stacking, threading, bending, welding, and trimming. While the welding is fast, the threading and alignment can be automated with proper fixtures. It is generally simpler than installing rigid wire-o spines but more involved than dropping pages onto a pre-opened metal ring.

Do the rings leave sharp edges?

The patent includes a step to trim off the “positioning bosses” used for alignment during welding. When done correctly, this results in a smooth, continuous ring. Proper mold design and trimming processes are key to ensuring no sharp edges remain.

Can this design be made and sold in the US?

The patent is in force in China. However, the public record shows no US counterpart for this specific patent. This means this particular Chinese patent does not restrict sales in the US. Always conduct a broader freedom-to-operate search to ensure no other US patents cover similar binding mechanisms.

Are you affiliated with the patent owner?

No. IP2M is an independent design and manufacturing service working from the public patent document.

Request a quote

Click Request a Quote below to see our email address - copy it, or open your email app with a ready-made message. Please mention patent CN115230365B in the subject.

Helpful details to include:

  • Your company and channel (notebook brand, educational publisher, promo supplier)
  • Target page count or thickness range
  • Ring colors and finish preferences
  • Estimated quantity of consumable strips vs. finished booklets
  • Timeline - when you would like samples and the first shipment

You can also reach us at (332) 203-9997.

Page editor: Daniel Chen, Product Research Editor · IP2M

Last updated November 7, 2026. If something on this page looks wrong, email [email protected] and we will check it against the patent.

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This page is based on the public patent document CN115230365B, assigned to Ningbo Chuangxin Binding Equipment Co., Ltd.. IP2M is an independent manufacturing service and is not affiliated with, endorsed by or licensed by the patent owner. Images marked as concept renderings are illustrations, not photos of an existing product. Patent status information is provided for reference only and is not legal advice; confirm freedom to operate for your market before production. Full disclaimer.