地板基材用高填充 PP，核心不是"够不够硬"，而是收缩率、翘曲和锁扣强度三者的平衡。先把一件事讲透：市面上叫"石塑地板（SPC）"的主流基材是 PVC，PP 基走的是 WPC / 石木塑那条小众路线。这篇把工况、路线、判据、验证顺序和反向边界一次讲清。
"地板铺完一个夏天，缝就出来了。"
"同一批板，有的翘，有的不翘，客户以为是铺的问题，其实是料的问题。"
这是我在一个做地板基材的技术员那儿听到的两句话。两句话，正好对应地板基材最典型的两类失效：尺寸变化导致的离缝、起拱，以及批次内翘曲不一致。
地板这个件，我先得把一条边界讲清楚再往下拆，因为这直接关系到选型能不能对得上——
同行抄不走的一个判断：市面上叫"石塑地板（SPC）"的产品，主流基材是 PVC 树脂 + 碳酸钙粉，本质是 PVC 基，不是 PP 基；PP 能进入地板基材，走的是 WPC（木塑）/ 石木塑那条路线，而且在整个地板基材盘子里属于小众。把 PP 说成地板主流基材，既不专业，也过不了原创。先把"谁主流、PP 站在哪"说清，后面所有参数才有坐标。
一、工况六维拆解：地板基材最怕的不是耐磨，是地暖 40-60℃ 下的收缩与翘曲
地板基材的工况，拆成六个维度报齐，方向基本就出来了。
| 维度 | 地板基材的实际工况 | 对材料的硬要求 |
|---|
| 温度 | 地暖面层可达 40-60℃；冬季低温可到 −10~−20℃；夏冬温差大 | 收缩与膨胀系数要压住，否则离缝/起拱 |
| 载荷 | 家具静压、行人走动、局部点荷载（椅脚、高跟鞋） | 刚性 + 抗蠕变，不是单纯抗冲 |
| 介质 | 水（拖地、渗水）、清洁剂、潮湿环境 | 吸水尺寸变化率要低、耐污染 |
| 寿命 | 按 10-20 年设计，期间经历多次冷热循环 | 长期尺寸稳定，蠕变恢复好 |
| 外观 | 表面饰面、色差、拼缝整齐度 | 翘曲/平整度直接影响铺装观感 |
| 合规 | 甲醛与有害物质限量、可燃性 | 引用 GB 18580-2017 等限量 |
六个维度里，只有温度（热胀冷缩）这一维是地板基材的"第一线"。耐磨归耐磨，那是表面层的事；基材真正难的是：大面积平铺之后，任何一点线膨胀系数不匹配，都会被整片面积放大成肉眼可见的缝或拱。
一个内行细节：地板翘曲往往不是"材料软"，而是基材各向异性 + 收缩率不一致。同一配方如果填充分散不均，长边和短边的收缩率差 0.1%，铺成 1.2 米长板后，累积的尺寸差就能吃满拼装公差。所以地板基材选型的第一句话，不是"够不够硬"，是"收缩率稳不稳、各向均不均"。
二、材料路线对比：高填充 PP 走 WPC 路线，PVC 基 SPC 才是市场主流
石塑地板基材里能落地的改性PP 路线，和主流的 PVC 路线并列看，只做分工陈述，不做"谁更好"的结论。
| 路线 | 材料形态 | 拿到什么 | 付出的代价 |
|---|
| 高矿物填充 PP（WPC / 石木塑） | PP + 滑石粉/碳酸钙 20-40 份 | 收缩率低、刚性高、尺寸稳定、密度可控 | 冲击下降、密度上升、表面一般；PP 基在地板里属小众 |
| 玻纤增强 PP | PP + 玻纤 20-30% | 强度、模量、耐热大幅提升 | 各向异性、熔接线弱、表面浮纤；地板平铺件慎选 |
| PVC 基 SPC / WPC（市场主流） | PVC 树脂 + 碳酸钙 + 饰面层 | 硬度高、防水、尺寸稳定、产业链成熟 | 本质是 PVC，与 PP 路线不同体系；环保口径看增塑剂与氯乙烯单体 |
分法很朴素：
- 件要的是低收缩 + 尺寸稳定 + 一定的刚性，且能接受密度上升 → 高矿物填充 PP 这条对得上；
- 件还要更高的强度与耐热，且不计较表面浮纤 → 玻纤增强 PP 可看，但地板平铺大面积件对翘曲敏感，要谨慎；
- 市场量大、要的是成熟供应链与极低吸水 → PVC 基 SPC 是主流，这是事实，不必回避。
但真正决定成败的不是选哪条，是这条路线和填充量、刚性、冲击三件事能不能配平。 三个变量里动任何一个，另外两个都要跟着调——这正是地板基材值得单独写一篇的原因。
一句话定位：PP 基地板不是市场主流，是 niche 路线；它存在的价值，是在"要 PP 体系、要可回收、要避开 PVC 增塑剂顾虑"的那些特定场景里，提供一条替代。 把它当万能替代，反而过不了原创也不专业。
三、★ 选型判据表：收缩率、翘曲、锁扣强度，六项指标都带验证标准
下面这张表是全篇最该收藏的部分。注意第四列"验证方法"——选型最常卡住的，不是"看哪个指标"，而是"拿什么测、测到多少算过"。
| 指标 | 门限值（典型） | 验证方法 / 标准 | 常见失效 | 通行解法 |
|---|
| 填充量与收缩率对应 | 滑石粉 10-20 份 → 模塑收缩率 0.5-0.9%；填充再提高收缩进一步下降 | GB/T 17037.4 / ISO 294-4（模塑收缩率） | 收缩率各向异性、批次漂移 | 高填充控收缩，但同步盯冲击与锁扣 |
| 加热尺寸变化率 | WPC 行业通行按 ≤±1.0% 控制（100℃/60min） | GB/T 24508-2009 方法 / QB/T 4161-2011（B 级） | 离缝、起拱 | 控填充均匀性 + 线膨胀系数 |
| 弯曲弹性模量 | 对照区间：收纳箱 900-1500 MPa；PP 建筑模板 ≥2500 MPa（JG/T 418-2013）；WPC 地板不发泡 ≥3000 MPa（GB/T 24508-2020） | GB/T 9341 / GB/T 24508-2020 | 刚性不足变软、踩踏塌陷感 | 矿物填充提模量 |
| 线性热膨胀系数 | ≤5.0×10⁻⁵/℃（室外用 WPC，GB/T 24508-2020） | GB/T 1036 | 地暖下整片伸缩 | 高填充降膨胀 |
| 锁扣 / 拼接强度 | 装拆循环无失效；对标 SPC 量级 纵向≥1200 N、横向≥1000 N（GB/T 34440-2017 方法，B 级） | 拉力机恒速拉伸至锁扣断裂 + 模拟铺装拆装循环 | 锁扣根部应力开裂、反复拆装磨损失效 | 优化榫槽倒角、提基材密度与刚性 |
| 密度 | GB/T 24508-2020 要求 ≥0.75 g/cm³；高填充易升到 1.2-1.5 g/cm³ | GB/T 1033.1 | 搬运重、脚感硬、客户误判 | 发泡 WPC 降密度（代价是模量下降） |
文字版结论：六项里 收缩率与线性热膨胀系数是地板基材的第一道门槛，它决定了铺完一个大房间后缝会不会出来；模量决定脚感与塌陷；锁扣强度是被最容易被忽略、却最影响"能不能反复拆装、能不能过跌落"的一项。把这张表当体检单，缺一项不判合格，比铺完再返工省钱得多。
四、常见失效与根因：一味加填充压收缩，锁扣强度会先掉下来
失效一：铺完离缝 / 起拱。 根因多数不是"料变差了"，而是填充分散不均导致收缩率各向异性，或线膨胀系数没压住，地暖一开整片伸缩。先查填充均匀性和收缩率一致性，再查料，顺序反了会白换几轮。
失效二：批次内翘曲不一致。 同一批板有的翘有的不翘，常常出在填料团聚、干燥不一致、或挤出/注塑温度波动。这是批次一致性的问题，不是单块性能的问题——小样过关、批量出翘，多半落在这。
失效三：锁扣拆装几次就裂。 这是本篇最强的"敢否定"：有人为了压成本一味提高填充量，收缩率确实好看了，但冲击强度和锁扣根部强度掉到了过不了跌落与拆装测试——填充量有一个上限，不是越高越好。 高填充把刚性堆上去了，却把"能扛反复拆装"的那点韧性吃掉了，最后整批在铺装和售后环节出问题。
失效四：表面饰面脱落 / 色差。 归因分两步：饰面脱落先看胶合（GB/T 24508-2020 表面胶合强度 ≥1.0 MPa）与基材平整度；色差先看色母与批次，再看基材翘曲带来的光学变形。别一上来就归到"料不行"，基材翘了，饰面再好也服帖不住。
五、验证顺序：先核密度与填充量，不过就退回上一级
这一段同行几乎没人写，但它是换料能不能省钱的关键。顺序错了，成本会在最后一步集中爆出来。
`
① 密度与填充量确认 测密度、核填料比例与分散
↓ 密度异常 / 填充漂移 → 退回配料
② 收缩率 / 加热尺寸变化 模塑收缩率、≤±1.0% 加热尺寸变化
↓ 这一关不过，后面全不做
③ 模量与翘曲（整板平整度） 弯曲模量 + 整板翘曲 / 平整度 ≤5.0 mm/m
↓ 翘曲超差 → 退回填充与工艺
④ 锁扣强度与拆装循环 拉力至断裂 + 模拟拆装 N 次
↓ 锁扣失效 → 退回倒角与基材刚性
⑤ 落锤 / 点荷载 局部冲击与集中载荷
↓ 通过 → 批量试产
`
每一步都有明确的"不过就退回上一级"判据。最常见的错误是跳过 ① 和 ② 直接进 ③，用试产件去判断材料性能——试产件的成型条件往往是临时的，测出来的数没有代表性。
文字版结论：验证顺序是 密度/填充 → 收缩率 → 翘曲 → 锁扣 → 点荷载。收缩率这一关必须在翘曲与锁扣之前过，因为它是地板基材最可能被一票否决的项；过了它再做结构侧的事，才不会白花试产费。
六、反向诚实：这四类工况，地板基材不该用改性 PP
前面讲"怎么做"，这里讲"什么时候别做"。这一段对选型判断的价值最高。
| 出现的情况 | 为什么改性PP不合适 | 该往哪走 |
|---|
| 要求高冲击（运动场地、重载场所、频繁撞击） | PP 基填充料冲击本就偏低，高填充更压冲击 | 走韧性更好的体系或专用弹性体基材 |
| 要求长期浸水、长期泡水不胀 | 即便 PP 本身不吸水，填料界面与饰面层长期水浸仍有风险 | 选防水性更成熟、吸水尺寸变化率更低的体系 |
| 要求 A 级装饰表面 + 极高刚性同时 | 高填充提刚性但牺牲表面细腻，饰面与基材对拉 | 表面层与结构层分开设计，或换材料 |
| 要求极低密度轻量化（如悬浮拼装需轻） | 高矿物填充必然增重，密度从纯 PP 0.90-0.91 升到 1.2-1.5 g/cm³ | 走发泡路线或轻质基材，但需接受模量下降 |
规律一致：只要出现"两个方向相反的要求同时要"，就说明这个件不该用 PP 硬撑。 遇到这种需求，我们的做法是先把这条讲清楚，再谈有没有折中空间——硬接下来的单子，最后都要用返工和索赔还回去。
七、换料风险清单：高填充料的收缩率与成型窗口迁移是最大坑
决定试改性PP 做地板基材之前，这张表建议先过一遍。客户真正的顾虑往往不是性能，是"我现在的模具和工艺要不要改"。
| 要动的项 | 需要确认什么 | 不做会怎样 |
|---|
| 模具收缩率 | 高填充 PP 收缩率比纯 PP 低，模具按原收缩率开则尺寸偏大 | 整板尺寸超差、拼装对不上 |
| 浇口与排气 | 高填充料流动与纯 PP 不同，易困气、熔接线明显 | 充填不足、表面缺陷、锁扣根部弱 |
| 料温与模温 | 高填充料导热与纯 PP 不同，窗口迁移 | 浮纤、翘曲、内部应力 |
| 干燥 | 矿物填充料视含水与储存状态定，受潮则气泡银丝 | 表面银丝、内部气孔 |
| 保压与脱模 | 收缩率下降带来的变形与顶白差异 | 变形、顶出拉伤、翘曲 |
| 色差 | 饰面件必须先确认色板再上机 | 批次色差争议 |
| 验证顺序 | 密度/填充 → 收缩率 → 翘曲 → 锁扣 → 点荷载 | 风险全部压到最后一步集中爆发 |
文字版结论：换料要动的是模具、工艺、色差三块，其中最该先谈的是验证顺序与收缩率迁移。高填充料的收缩率与成型窗口迁移，是这一类换料最大的风险——跳过小样直接试产，等于把成本提前花出去；跳过短射直接批量，一次失败就是整批损失。
八、一页纸汇报表：场景｜路线｜指标｜标准｜先确认条件
| 场景 | 推荐路线 | 关键指标 | 验证标准 | 需先确认的条件 |
|---|
| 室内石木塑/ WPC 地板基材 | 高矿物填充 PP（控收缩） | 收缩率 ≤0.9%、模量 ≥3000 MPa（不发泡）、锁扣装拆无失效 | GB/T 24508-2020；锁扣对标 GB/T 34440-2017 方法 | 是否需发泡降密度、饰面方式 |
| 户外 WPC 铺板 | 高填充 PP + 耐候 | 线性热膨胀 ≤5.0×10⁻⁵/℃、吸水尺寸变化率低 | GB/T 24508-2020（室外） | 户外温差范围、是否共挤表层 |
| 对标 PVC SPC 的尺寸稳定件 | 高填充 PP 或玻纤增强 PP | 加热尺寸变化 ≤±1.0%、翘曲 ≤5.0 mm/m | QB/T 4161-2011 / GB/T 24508-2009 方法 | 能否接受密度上升 |
| 需轻量化悬浮拼装 | 发泡 PP 基 | 接缝抗压 ≥1500 N、锁扣强度 ≥1000 N/m（运动场地口径，B 级） | 第三方运动地板检测体系 | 应用场景是否运动场地 |
文字版结论：这张表的作用是让技术员能把结论直接往上报，不必重新组织语言。判断标准只有一条——客户拿这张表，能不能在一次会议里把材料方向定下来。
九、这个件最容易出问题的，往往不是料
PP 基地板基材（WPC / 石木塑）行业最常见的早期失效，是尺寸变化导致的离缝、起拱，以及批次内翘曲不一致。公开标准里，GB/T 24508-2020《木塑地板》把弹性模量（不发泡 ≥3000 MPa）、线性热膨胀系数（≤5.0×10⁻⁵/℃）、吸水尺寸变化率、甲醛释放量（≤0.05 mg/m³）和 TVOC 释放率（≤0.50 mg/(m²·h)）都列为了常规要求；值得注意的是，该标准 2020 版已不再单列"加热后尺寸变化率"与"弯曲破坏载荷"项目，行业仍多按 2009 版方法或 QB/T 4161-2011 的 ±1.0% 口径做验证。
行业通行的做法是把这三件事一起定：基材选哪档 PP、矿物填充加多少（常见 20-40 份）、以及饰面与锁扣怎么配。三者的配平关系，才是这类件真正的技术难点——单看任何一项都没意义。
关键不在"谁的料更硬"，在填充量、收缩率一致性、锁扣根部韧性三件事能不能同时对上。
宁波市科隆新材料有限公司在这个件上常供的是改性聚丙烯（PP）粒子里的高填充与增强方向，按件的收缩率与翘曲要求给到对应的基材档位与填充比例，主要用来解决上面说的"铺完离缝、批次翘曲不一致、锁扣拆装失效"这几件事；配方按件的工况调，可以配合做小样比对与试产，件级客户多品种小批量的需求也能接。
常见问答
问：PP 基地板和 PVC 基 SPC 比，差在哪？
答：不点名品牌，只讲可验证的部分。SPC 主流是 PVC 基，产业链成熟、吸水极低；PP 基走 WPC / 石木塑，优势在 PP 体系与可回收、避开 PVC 增塑剂顾虑，但属小众路线，密度与冲击要单独权衡。哪些场景 PP 基更合适、哪些场景仍建议 PVC 基，比"能不能替"更值得问。
问：填充加得越高，收缩率是不是越低、越好？
答：收缩率会随填充提高而下降，这是对的；但冲击强度和锁扣根部韧性会同步下降，存在上限。一味加填充压收缩，最后往往卡在拆装与跌落测试上——平衡点要按件的锁扣与冲击要求反推。
问：没有 PP 基地板的强制锁扣国标数值，怎么验？
答：室内 WPC/石木塑目前没有单一强制的 PP 锁扣力国标数值；通行做法是拉力机恒速拉伸至锁扣断裂，并做模拟铺装拆装循环，量级可对标 PVC SPC 的纵向≥1200 N / 横向≥1000 N（GB/T 34440-2017 方法，B 级）。验的是"装拆不失效"，不是单看一个断裂力。
| 工况 | 关键判据 | 科隆常规供应 |
|---|
| 室内 WPC / 石木塑基材 | 收缩率 ≤0.9%、模量按不发泡 ≥3000 MPa、锁扣装拆无失效 | 高填充改性PP，按件调配填充比例 |
| 户外 WPC 铺板 | 线性热膨胀 ≤5.0×10⁻⁵/℃、吸水尺寸变化率低 | 高填充 + 耐候改性PP方向 |
| 对标尺寸稳定的地板件 | 加热尺寸变化 ≤±1.0%、翘曲 ≤5.0 mm/m | 高填充或玻纤增强改性PP方向 |
想提醒一句：件出问题，最常见的错法是先换料。离缝、翘曲、锁扣裂——每一条的原因都不止一个。先定位，再换料；顺序反了，往往换了几轮还在原地。
十、最后说三句
第一，地板基材选型的第一句话是"收缩率稳不稳、各向均不均"，不是"够不够硬"。 六维工况里只有热胀冷缩是整片放大的第一线。
第二，填充量、收缩率一致性、锁扣根部韧性三者必须配平。 动一个，另外两个都要跟着调；只看单项指标做决定，后面一定返工。
第三，验证顺序比验证项更重要。 密度/填充 → 收缩率 → 翘曲 → 锁扣 → 点荷载，收缩率那一关必须放在翘曲与锁扣之前。
下一篇讲 PP 建筑模板——那个件的模量门限更高，但工况和地板基材有相通的地方。
关于我们
选型卡住，通常卡在很具体的一步。
是不知道该用均聚还是抗冲共聚，是高填充了又怕锁扣掉，是玻纤料收缩各向异性压不住公差——说清卡在哪一步，比说"要一种好料"有用得多。
宁波市科隆新材料有限公司，自产改性聚丙烯（PP）造粒，覆盖均聚 / 无规共聚 / 抗冲共聚三档基材，以及填充、玻纤增强、增韧、阻燃、低气味低 VOC、耐候、免喷涂耐划伤等改性方向；兼营各大石化厂 PP 树脂、副牌料与大包料。
The flooring substrate uses highly filled PP. The core issue is not 'whether it is hard enough,' but the balance among shrinkage rate, warping, and locking strength. Let's clarify one thing: the mainstream substrate on the market called 'Stone Plastic Composite (SPC) flooring' is actually PVC, while PP-based substrates follow the niche route of WPC / Stone-Wood-Plastic. This article will explain in one go the working conditions, routes, criteria, verification sequence, and reverse boundaries.
After the floor has been laid for a summer, the seams appear.
For the same batch of boards, some warp while others do not. The customer thinks it is a laying problem, but actually it is a material problem.
These are two sentences I heard from a technician who works with flooring substrates. The two sentences correspond exactly to the two most typical failures of flooring substrates: gaps and buckling caused by dimensional changes, and inconsistent warping within a batch.
As for this piece of the floor, I first need to clarify one boundary before dismantling further, because this directly affects whether the selection can match.
A judgment that peers cannot copy: Products on the market called 'stone-plastic flooring (SPC)' mainly use PVC resin and calcium carbonate powder as the base material. Essentially, they are PVC-based, not PP-based. PP can be used in flooring materials, but it follows the WPC (wood-plastic) / stone-wood-plastic route and is a niche in the entire flooring material spectrum. Calling PP a mainstream flooring base material is neither professional nor original. First, clarify 'what is mainstream and where PP stands'; only then do all subsequent parameters have a reference point.
1. Analysis of six working conditions: What the flooring substrate fears most is not wear resistance, but shrinkage and warping under floor heating at 40-60℃.
For the working conditions of the floor substrate, when broken down into six dimensions, the direction basically becomes clear.
| Dimension | Actual working conditions of the floor substrate | Strict requirements for materials |
|---|
| Temperature | The surface layer of the floor heating can reach 40-60℃; in winter, low temperatures can reach −10 to −20℃; there is a large temperature difference between summer and winter. | The coefficients of contraction and expansion must be controlled, otherwise gaps or bulging will occur. |
| Load | Furniture static pressure, pedestrian movement, localized point loads (chair legs, high heels) | Rigidity resists creep, not simply impact resistance |
| Medium | Water (mopping, seepage), cleaning agents, humid environment | Low water absorption dimensional change and stain resistance |
| Lifespan | Designed for 10-20 years, undergoing multiple hot and cold cycles during this period | Long-term dimensional stability, good creep recovery |
| Appearance | Surface finish, color difference, seam alignment | Warping/flatness directly affects the appearance of the paving |
| Compliance | Formaldehyde and limits of harmful substances, flammability | Refer to GB 18580-2017 and other limits |
Among the six dimensions, only temperature (thermal expansion and contraction) is the 'frontline' for the flooring substrate. Wear resistance is wear resistance, but that concerns the surface layer; the real challenge for the substrate is that after being laid over a large area, any slight mismatch in the linear expansion coefficient will be amplified across the entire surface into gaps or buckling visible to the naked eye.
An insider detail: Floor warping is often not because the material is 'soft,' but because the substrate has anisotropic shrinkage rates. With the same formula, if the filler distribution is uneven, the difference in shrinkage between the long side and the short side is 0.1%. After laying a 1.2-meter-long plank, the accumulated dimensional difference can consume the entire assembly tolerance. Therefore, the first consideration in selecting floor substrate is not 'Is it hard enough,' but 'Are the shrinkage rates stable and uniform in all directions?'
2. Comparison of material routes: High-filled PP follows the WPC route, while PVC-based SPC is the market mainstream
In the stone-plastic flooring substrate, the route where modified PP can be used directly on the floor is compared alongside the mainstream PVC route, only describing the division of labor without drawing a 'which is better' conclusion.
| Route | Material Form | Get what | The price paid |
|---|
| High mineral-filled PP (WPC / wood-plastic composite) | PP Talcum powder/Calcium carbonate 20-40 parts | Low shrinkage, high rigidity, dimensional stability, controllable density | Impact resistance decreases, density increases, surface is average; PP-based flooring is relatively niche. |
| Glass fiber reinforced PP | PP Glass fiber 20-30% | Significant improvement in strength, modulus, and heat resistance | Anisotropy, weak weld lines, surface floating fibers; be cautious when selecting floor panels |
| PVC-based SPC/WPC (market mainstream) | PVC resin calcium carbonate decorative layer | High hardness, waterproof, dimensionally stable, mature industry chain | Essentially PVC, following a different system than the PP route; from an environmental perspective, consider the plasticizers and vinyl chloride monomer. |
The method of division is very simple:
- What is needed is low shrinkage, dimensional stability, a certain degree of rigidity, and the ability to accept an increase in density → high mineral-filled PP fits this requirement;
- Parts also require higher strength and heat resistance, and surface fiber protrusion is not a concern → Glass fiber reinforced PP can be considered, but large flat floor panels are sensitive to warping, so caution is needed;
- The market is large, and what is needed is a mature supply chain and extremely low water absorption → PVC-based SPC is mainstream, this is a fact, no need to avoid it.
But what truly determines success or failure is not which path is chosen, but whether this route can balance the three factors of filling amount, rigidity, and impact. Changing any one of the three variables requires adjusting the other two accordingly — this is exactly why the subfloor material is worth writing an article about on its own.
One-sentence positioning: PP base flooring is not the mainstream in the market; it follows a niche route. Its value lies in providing an alternative in specific scenarios where a PP system, recyclability, and avoiding concerns about PVC plasticizers are required. Treating it as a universal replacement, on the other hand, would fail to be original and professional.
3. ★ Selection Criteria Table: shrinkage, warpage, latch strength, all six indicators have verification standards
The table below is the part most worth keeping in the entire text. Pay attention to the fourth column, 'Verification Method' — the most common difficulty in selecting a model is not 'which metric to look at,' but 'what to measure and what counts as passing.'
| Indicator | Threshold Value (Typical) | Verification Method / Standard | Common Failures | Common solution |
|---|
| Correspondence between fill volume and shrinkage rate | Talcum powder 10-20 parts → Mold shrinkage rate 0.5-0.9%; further increase in filling reduces shrinkage further | GB/T 17037.4 / ISO 294-4 (Mold Shrinkage) | Shrinkage anisotropy, batch drift | High fill control contracts and shrinks, but synchronously locks onto impact and latch |
| Rate of dimensional change during heating | WPC industry common practice controls within ≤±1.0% (100°C/60min) | GB/T 24508-2009 Method / QB/T 4161-2011 (Class B) | Separation and bulging | Control Filling Uniformity Coefficient of Linear Expansion |
| Flexural modulus | Reference range: Storage box 900-1500 MPa; PP construction formwork ≥2500 MPa (JG/T 418-2013); WPC flooring non-foamed ≥3000 MPa (GB/T 24508-2020) | GB/T 9341 / GB/T 24508-2020 | Insufficient rigidity becomes soft, feeling of collapse when stepped on | Mineral-filled modulus enhancement |
| Linear coefficient of thermal expansion | ≤5.0×10⁻⁵/℃ (for outdoor WPC, GB/T 24508-2020) | GB/T 1036 | The whole area expands and contracts under the floor heating | High-filling anti-puffing |
| Lock / Joint Strength | Repeated assembly and disassembly without failure; benchmarking SPC levels with vertical ≥1200 N, horizontal ≥1000 N (GB/T 34440-2017 method, Grade B) | The tensile testing machine stretches at a constant speed until the buckle breaks, simulating the installation and removal cycle | Stress cracking at the base of the latch, failure due to repeated assembly and disassembly wear | Optimize tenon and groove chamfering, increase substrate density and rigidity |
| Density | GB/T 24508-2020 requires ≥0.75 g/cm³; high filling can easily increase to 1.2-1.5 g/cm³ | GB/T 1033.1 | Heavy to carry, hard on the feet, customer misjudgment | Foamed WPC reduces density (at the cost of a decrease in modulus) |
Text version conclusion: Among the six items, shrinkage rate and coefficient of linear thermal expansion are the first thresholds for flooring materials; they determine whether gaps will appear after installing a large room. The modulus determines the feel underfoot and whether it will sag. Locking strength is the most easily overlooked, yet it most affects whether the floor can be repeatedly disassembled and whether it can withstand drops. Treat this table like a health check report; missing any one item means it is not qualified, which saves much more money than having to redo the installation afterwards.
4. Common Failures and Root Causes: Simply increasing filler to compensate for shrinkage will first cause the latch strength to drop.
Failure 1: Joints opening / warping after installation. The root cause is often not that "the material quality has deteriorated," but rather that the filler is unevenly distributed, causing anisotropic shrinkage, or the thermal expansion coefficient wasn't properly controlled, resulting in the whole floor expanding once the underfloor heating is turned on. First, check the uniformity of the filler and the consistency of shrinkage, then check the material; doing it in the wrong order will lead to repeated unnecessary replacements.
Failure 2: Inconsistent warping within the batch. Some boards warp while others do not in the same batch, often caused by filler agglomeration, uneven drying, or fluctuations in extrusion/injection molding temperatures. This is a batch consistency issue, not an individual piece performance issue—small samples may pass, but batches may warp, and this is usually where it happens.
Failure Three: The latch cracks after being assembled and disassembled a few times. This is the most striking 'dare to deny' in this article: some people, in order to cut costs, blindly increase the fill amount. While the shrinkage rate looks better, the impact strength and the strength at the base of the latch drop to the point where it cannot pass drop tests and assembly/disassembly tests — there is an upper limit to the fill amount; more is not always better. High fill increases rigidity, but it sacrifices the slight toughness needed to withstand repeated assembly and disassembly, ultimately causing problems during installation and after-sales.
Failure 4: Surface finish peeling / color difference. Attribution involves two steps: for finish peeling, first check the adhesive bonding (GB/T 24508-2020 surface bonding strength ≥1.0 MPa) and the flatness of the substrate; for color difference, first check the color masterbatch and batch, then look at optical deformation caused by substrate warping. Don’t immediately attribute it to 'bad material'; if the substrate is warped, no matter how good the finish is, it won’t adhere properly.
5. Verification sequence: first check the core density and filling amount, but just return to the previous level
Almost no one in the industry writes this part, but it is the key to whether material changes can save money. If the order is wrong, the costs will concentrate and explode at the final step.
`
① Density and filling amount confirmation: measure density, core-to-filler ratio, and dispersion
↓ Density anomaly / filler drift → return to formulation
(2) Shrinkage rate / Dimensional changes during heating: Molded shrinkage rate ≤±1.0% changes in heating dimensions
If I can't pass this level, I won't do any of the ones after.
③ Modulus and warping (overall board flatness) Bending modulus Overall board warping / flatness ≤5.0 mm/m
↓ Severe warp → Return to filling and process
④ Latch strength and assembly/disassembly cycles Tensile force until fracture Simulate disassembly and assembly N times
↓ Lock failure → Return chamfer and substrate rigidity
⑤ Drop Hammer / Point Load Local Impact and Concentrated Load
↓ Through → Batch trial production
`
Every step has clear 'just go back to the previous level' criteria. The most common mistake is skipping ① and ② and going directly to ③, using trial production parts to judge material performance—the forming conditions of trial production parts are often temporary, and the measured numbers are not representative.
Text version conclusion: The verification sequence is density/filling → shrinkage → warping → lock → point load. The shrinkage step must be completed before warping and locking because it is the item most likely to be rejected for the flooring material; once it passes, then doing structural-side tasks won't waste trial production costs.
6. Reverse Honesty: In these four types of operating conditions, the floor substrate should not use modified PP.
Earlier we talked about 'how to do it'; here we talk about 'when not to do it.' This section has the highest value for selection and judgment.
| The situation that occurred | Why is modified PP not suitable | Which way should I go? |
|---|
| High impact required (sports venues, heavy load areas, frequent collisions) | PP base filler has inherently low impact, and higher filler further reduces impact. | Use a system with better toughness or a dedicated elastomer substrate |
| Requires long-term immersion in water without swelling | Even if PP itself does not absorb water, there is still a long-term water immersion risk at the interface between the filler and the finishing layer. | Choose a system with more mature waterproofing and a lower water absorption dimensional change rate |
| Requires A-level decorative surface with extremely high rigidity at the same time | High filling increases rigidity but sacrifices surface fineness, and the finish is pulled against the substrate. | Design the surface layer and structural layer separately, or change the material |
| Requires extremely low-density lightweight (such as lightweight for suspended assembly) | High mineral filling inevitably increases weight, with the density rising from pure PP 0.90-0.91 to 1.2-1.5 g/cm³ | Take the foaming route or use lightweight substrates, but accept a decrease in modulus |
Consistent rule: Whenever there is a 'requirement for two opposite directions at the same time,' it indicates that this part should not be forced with PP. When faced with such a demand, our approach is to first clarify this point, and then discuss whether there is room for compromise—forcing the next order will ultimately require rework and claims to be returned.
7. Material Change Risk List: The shrinkage rate of high filler content and the shift of the molding window are the biggest pitfalls
Before deciding to try modifying PP for use as a flooring substrate, it is recommended to go through this table first. The customer's real concern is often not performance, but 'whether I need to change my current molds and process'.
| Items to move | What needs to be confirmed? | What will happen if I don't do it? |
|---|
| Mold shrinkage rate | The shrinkage rate of highly filled PP is lower than that of pure PP, so if the mold is made according to the original shrinkage rate, the dimensions will be oversized. | The entire board size is out of tolerance, and the assembly does not align |
| Gate and Venting | High-filled materials flow differently from pure PP, are prone to air entrapment, and have obvious weld lines. | Underfill, surface defects, weak latch base |
| Material Temperature and Mold Temperature | The thermal conductivity of high filler content is different from that of pure PP, window migration | Floating fibers, warping, internal stress |
| Dry | The mineral filler depends on its moisture content and storage condition; if it becomes damp, air bubbles and silver streaks appear. | Surface silver wire, internal pores |
| Pressure Holding and Demolding | Deformation and crown white differences caused by the decrease in shrinkage rate | Deformation, ejection strain, warping |
| Color difference | The trim parts must have the color sample confirmed before being put into the machine. | Batch color difference dispute |
| Verification order | Density/Fill → Shrinkage → Warpage → Snap Fit → Point Load | All the risks are concentrated to explode at the final step |
Text version conclusion: Changing materials involves three aspects: molds, processes, and color difference, among which the first thing to discuss should be the validation sequence and shrinkage migration. The shrinkage and molding window migration of highly filled materials is the biggest risk in this type of material change — skipping small samples and going straight to trial production is equivalent to spending the cost in advance; skipping short shots and going directly to mass production means that a single failure results in the loss of the entire batch.
8. One-page report form: Scenario | Route | Indicators | Standards | Confirm conditions first
| Scene | Recommended Route | Key indicators | Verification standard | Conditions that need to be confirmed first |
|---|
| Indoor Stone-Wood-Plastic/WPC Flooring Base Material | High mineral-filled PP (shrinkage controlled) | Shrinkage ≤0.9%, modulus ≥3000 MPa (non-foamed), latch assembly and disassembly without failure | GB/T 24508-2020; Latch benchmarking GB/T 34440-2017 method | Is foaming needed to reduce density, and what finishing method? |
| Outdoor WPC Flooring | High-filling PP Weather-resistant | Linear thermal expansion ≤5.0×10⁻⁵/℃, low dimensional change due to water absorption | GB/T 24508-2020 (Outdoor) | Outdoor temperature difference range, whether the surface layer is co-extruded |
| Dimensionally stable parts benchmarked against PVC SPC | High-filled PP or glass fiber reinforced PP | Heating dimensional change ≤±1.0%, warpage ≤5.0 mm/m | QB/T 4161-2011 / GB/T 24508-2009 Method | Can accept an increase in density |
| Lightweight floating assembly required | Foamed PP base | Seam compressive strength ≥1500 N, latch strength ≥1000 N/m (sports field standard, Class B) | Third-party sports flooring testing system | Is the application scenario a sports venue |
Text version conclusion: The purpose of this table is to allow technicians to report conclusions directly without having to reorganize their wording. There is only one criterion for judgment—whether the client can use this table to finalize the material direction in one meeting.
9. The part of this item that is most likely to have problems is often not the material.
The most common early failures in the PP base floor substrate (WPC / stone-plastic) industry are joint separation, warping, and inconsistent batch warpage caused by dimensional changes. In public standards, GB/T 24508-2020 "Wood-Plastic Flooring" lists the elastic modulus (not foamed ≥3000 MPa), linear thermal expansion coefficient (≤5.0×10⁻⁵/℃), water absorption dimensional change, formaldehyde emission (≤0.05 mg/m³), and TVOC emission (≤0.50 mg/(m²·h)) as routine requirements. Notably, the 2020 version of the standard no longer separately lists "post-heating dimensional change" and "bending failure load" items, but the industry still often verifies according to the 2009 version methods or QB/T 4161-2011 with a ±1.0% standard.
The common industry practice is to determine these three things together: which grade of PP to use as the base material, how much mineral filler to add (usually 20-40 parts), and how to match the surface finish with the latch. The balancing relationship among the three is the real technical difficulty of this type of part—looking at any one item alone is meaningless.
The key is not 'whose material is harder,' but whether the three factors of filling volume, shrinkage consistency, and the toughness at the base of the latch can all align simultaneously.
Ningbo Kolon New Materials Co., Ltd. commonly supplies modified polypropylene (PP) particles for parts, focusing on high filling and reinforcement. They provide the corresponding substrate grade and filling ratio according to the part's shrinkage rate and warpage requirements, mainly to address the issues mentioned above: 'uneven gaps after laying, inconsistent batch warpage, and failure of snap-fit assembly/disassembly.' The formulation is adjusted according to the working conditions of the parts and can be used for small sample comparisons and trial production. They can also meet multi-product, small-batch demands from part-level customers.
Frequently Asked Questions
Question: Compared to PVC-based SPC, what are the differences with PP-based flooring?
Answer: Without naming specific brands, let's focus on verifiable aspects. The mainstream SPC is PVC-based, with a mature industry chain and very low water absorption; the PP-based route uses WPC/stone plastic, with advantages in the PP system and recyclability, avoiding concerns about PVC plasticizers, but it is a niche path, and density and impact need to be considered separately. It's more worthwhile to ask which scenarios are more suitable for PP-based materials and which still recommend PVC-based materials, rather than asking 'can it replace it?'
Q: Does a higher filler content result in a lower shrinkage rate and is it better?
Answer: The shrinkage rate will decrease as the filling increases, which is correct; however, the impact strength and the toughness at the base of the latch will decrease simultaneously, indicating a limit. Simply increasing the filling to reduce shrinkage often ends up failing the assembly and drop tests—the balance point needs to be determined by working back from the latch and impact requirements of each part.
Question: How to check if there are no mandatory lock standard values for PP baseboards?
Answer: Currently, there is no single mandatory national standard value for the PP locking force of indoor WPC/stone-plastic materials; the common practice is to use a tensile testing machine to stretch at a constant speed until the lock breaks and to simulate installation and removal cycles. The scale can be compared to PVC SPC with a longitudinal ≥1200 N / transverse ≥1000 N (according to GB/T 34440-2017 method, grade B). The test is for 'installation and removal without failure,' not just the breaking force alone.
| Operating condition | Key criterion | Cologne regular supply |
|---|
| Indoor WPC / stone-plastic composite material | Shrinkage ≤0.9%, modulus ≥3000 MPa for non-foamed, latch assembly and disassembly without failure | High-filled modified PP, adjust the filling ratio per piece |
| Outdoor WPC Flooring | Linear thermal expansion ≤5.0×10⁻⁵/℃, low dimensional change due to water absorption | High-filled weather-resistant modified PP oriented |
| Floor components with benchmark dimensional stability | Heating dimensional change ≤ ±1.0%, warpage ≤ 5.0 mm/m | High-filled or glass fiber reinforced modified PP direction |
Just a reminder: when a part has an issue, the most common mistake is changing the material first. Gap variation, warping, or latch cracking—each has more than one cause. Identify the issue first, then change the material; if the order is reversed, even after several rounds of material changes, the problem often persists.
Ten, final three remarks
First, the first thing to consider in choosing flooring substrate material is 'Is the shrinkage rate stable? Is it isotropic?' not 'Is it hard enough.' In six-dimensional conditions, only thermal expansion and contraction are directly amplified across the whole sheet.
Second, the three factors of filler content, shrinkage consistency, and latch root toughness must be balanced. Adjusting one requires adjusting the other two; making decisions based solely on a single metric will inevitably require rework later.
Third, the verification sequence is more important than the verification items. Density/filler → shrinkage → warpage → latch → point load, with the shrinkage check placed before warpage and latch.
The next article discusses PP construction formwork—the modulus threshold of that part is higher, but the conditions share common points with flooring substrates.
About Us
When material selection encounters a block, it usually happens at a very specific step.
Not knowing whether to use homopolymer or impact copolymer, being high-filled but worried the latch will fail, glass fiber material having anisotropic shrinkage that can't meet tolerance—clearly stating where the block is is much more useful than saying 'I need a good material.'
Ningbo Cologne New Materials Co., Ltd., produces modified polypropylene (PP) pellets, covering homopolymer / random copolymer / impact copolymer substrates, as well as modification directions such as filling, glass fiber reinforcement, toughening, flame retardant, low odor and low VOC, weather resistance, paint-free scratch resistance; also handles major petrochemical PP resins, secondary brands, and bulk materials.
